Electronic device



April 1 s. J. CHERRY ETAL. v 2,398,578

ELECTRONIC DEVICE Filed July 4, 1942 INVENTORS '6'. J. C'l/EEEY z. c. WEE/V478 v 14/. a. IVOCHE'L Mwhm ATTORNEY Patented Apr. 16, 1946 UNITED STATES PATENT OFFICE ELECTRONIC DEVICE Sidney John Cherry, East Orange, Leo Carl Wei-=- ner, Bloomfield, and William John Knochel,

'Irvington, N. J

assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a

corporation of Pennsylvania Application July 4, 1942, Serial No. 449,752

1 Claim.

This invention relates to electronic devices and, more particularly, to a molded glass flare tube especially adapted for high frequency devices.

One of the factors limiting the frequency at which a vacuum tube may be operated is the length of the leads connecting the outer circuit to the electrodes. This is because the leads themselves offer appreciable impedance to current of high frequency.

In order to decrease the lead length it has been the practice to reduce the glass insulation between electrodes. This is Objectionable in that the voltages on the electrodes must accordingly be reduced, thereby limiting the power and frequency due to increased electron transit time.

One objection to the ordinary type of molded flare for use as part of an electron tube of high frequency is that in sealing on final assembly the inner parts of the tube are close to the fires used, thereby resulting in oxidation of said inner parts. This oxidization means that a longer exhaust is necessary, and the qualtiy of the tube may be 1m paired if the oxide formed breaks down and re-' leases gas during operation.

At high frequency the current through the leads to the electrodes causes these leads to reach a higher temperature than when merely used for a similar current at low frequency because of the greater skin effect. This lead heating limits the frequency and power output of the tube because of the danger of overheating the glass seals and releasing gas from the leads.

In the ordinary flare the connection of the exhaust tube presents a hazard, because heat must be applied close to the body of the said flare. This means that skilled labor must be used together with careful annealing after such operation.

When the ordinary flare is tipped off, part of the tip projects beyond the glass envelope, thus presenting the danger that it may be knocked off in handling.

With the foregoing in mind, it is one of the principal objects of our invention to produce a molded flare avoiding the enumerated difficulties to a great extent.

Another object of our invention is to produce a flare for electronic tubes, particularly such for high frequency, in which the leads are shortened as compared with those previously employed, thereby permitting the use of higher frequencies.

A further object of our invention is to increase the length of the insulation path in order to make it possible to use higher voltages, high power output, and higher frequencies.

A still further object of our invention is to produce a flare in which a greater proportion of the lead length is outside of the envelope, making it possible to plate with silver or other high conducting material without undesirable results, so that the resistance to high frequency may be materially reduced.

An additional object of our invention is to remove the point at which the exhaust tube is joined to the flare, as far from the body of the flare as possible, so that the glassing, or operation of the connecting of the parts, does not introduce heavy strains inthe flare proper.

Another object of our invention is to produce a flare so designed that a constriction is automatically provided where the exhaust tubulation will be tipped off, and at such a point that no glass tubing will project beyond the flare outline.

A further object of our invention is the production of a flare in which the line of 'flres used to fuse the same to the bulb does not intersect the innermet'al parts or electrodes, therebyavoid ing oxid-ization of said parts and possible subsequent release-of gas therefrom.

A still further object of our invention is the production of a flare in which the leads may be, to a great extent, outside of the envelope in order that they may run cooler because of the greater heat dissipating effect or air as compared with a vacuum, thereby making it possible to use higher current, voltage, and frequencies, with a greater output being made available.

Other objects and advantages of the invention, relating to the particular arrangement and construction of various parts, will become apparent as the description proceeds.

Referring to the drawing:

Fig. 1 is a fragmentary elevational view of an electronic tube embodying our invention.

Fig, 2 is a fragmentary axial sectional view of the flare portion of a tube as shown in Fig. 1, the glass envelope thereof being illustrated in dotted H lines.

Fig. 3 is a transverse sectional view on the line Referring to the drawing in detail, like parts being designated by like reference characters, there is shown an electronic tube l0 particularly adapted for high frequency, and comprising a vitreous flare portion ll, embodying our invention, and moreover connected to one end of a glass envelope portion l2 along the periphery of an outstanding flange l3. Such connection may be effected by means of gas fires, or electrically as described and claimed in the Dailey application, Serial No. 426,965, filed January 16, 1942, and owned by the assignee of the present application, although, because of the improvement in flare construction which results in removing the metal interior parts of the tube from the plane of sealing, it is not as necessary to use electrical sealing in the present instance, as it would be in the case of an envelope of the type described in said application.

In accordance with our invention, the flare l I comprises an inwardly-curved generally spherical body portion, inwardly offset with respect to its flange [3, which lies in a plane normal to the axis of the envelope [2. The curved body portion is connected to the flange 13 by an outwardly expanding generally frusto-conical portion of the Hare. Instead of having the generally frustoconical apertured bosses l4, l5, l6, l1 and 18, which are desirably uniformly arranged with their axes as elements of a cylinder coaxial with the device, projecting outwardly of the envelope 12, as in the device illustrated in the Dailey application, said bosses project inwardly or from the convex side of the curved body of said flare, and so carr the metal parts away from the plane of the seal [9 between the flare H and the envelope 12.

To further remove the action of the fires from the inner metal parts, the exhaust tube or tubulatioh 2| which may be initially connected to the exhaust stub 22 of the flare at 20, projects from the concave face of the curved body of the flare l I, rather than from the convex face from which the bosses [4 to I8, project, so that upon final sealing, the tip 22 of said exhaust tube will not project beyond the flange 13 of the flare, as'shown most clearly in Fig. 2.

By virtue of having the bosses Hi to 18, inclusive, project inwardly the bulk or greater portion of the length of the corresponding rigid lead-in posts or conductors 23, 24, 25, 26 and 21 are outside of the evacuated space of the envelope 12, that is, they are in the reentrant pockets around said members 23 to 21, inclusive, as indicated at 28 in Fig. 2, whereby they are more efliciently cooled by the surrounding air. They may be plated with silver, or other highly conductive metal, without danger of introducing readily reducible oxides into the interior of the envelope, with the risk of making the tube gassy during use.

As shown in Fig. 2, each conductor 23 to 21, inclusive, has its outer end threaded, as indicated at 29, for connection with an outside lead, and its inner end threaded, as indicated at 3|, for receiving nuts 32 and 33 for securing the pan member 34, which may serve as a base for the grid assembly, the supports of which are indicated at 35; or the cathode assembly, the supports for which are indicated at 36. In the present embodiment, the conductors 23, 25 and 21 are adapted to support the grid, while those designated 24 and 26 may support the cathode.

Each of said leads 23 to 21, inclusive, also carries a collar member 31 comprising an annular flat portion 38 directly connected to it, as by means of brazing material 39, and a generally cylindrical flange portion 4| connected to the inner edge portion of the corresponding one of the flare bosses, designated I4 to l8, inclusive, as by being embedded therein as shown most clearly at 42 in Fig. 2. The anode 43 of the device may be connected to the other edge portion 44 of the member or tube 12, as by having a Kovar or other suitable metal connecting flange portion 45 embedded therein, as shown most clearly in Fig. 1.

From the foregoing disclosure it will be seen that we have provided an improved flare which is advantageous particularly for electronic tubes for high frequency, in that the lead members, and particularly the portions enclosed in the envelope, may be considerably shortened, the insulation path for a given length of bulb or envelope may be lengthened, the exhaust tube extends in a direction opposite the conductor seals, thereby removing the glassing and tipping-off heat from the vicinity of said seals, the exhaust tip may be within the outline of the flare, the line of sealing is offset from the inner metal parts, and a large part of the leads are disposed outside of the evacuated space in the envelope, whereby they may be run cooler, adapting the tube for use with higher power.

Although a preferred embodiment of our invention has been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claim.

We claim:

An electronic device comprising a vitreous envelope, a flare for said envelope comprising an inwardly-curved generally spherical vitreous body portion, inwardly offset with respect to a peripheral flange thereof, lying in a plane normal to the axis of said envelope and to which it is connected by an outwardly-expanding generally frustoconical portion, said flange being sealed to one end or said envelope, five generally frusto-conical hollow apertured bosses uniformly arranged with their axes as elements of a cylinder coaxial with said device and extending inwardly from the inner side of said curved body portion, rigid leads passing axially through said bosses, each lead carrying a collar comprising a flat portion connected thereto and a generally cylindrical portion extending toward and embedded in the free edge of one of said bosses, a pair of non-adjacent leads serving for the support of an electrode to function as a cathode, a pan member secured to the three remaining leads as a base for a grid assembly, an electrode to function as an anode sealed to the end portion of said envelope remote from said flare, and a hollow boss extending from the central part of the convex side of said curved body portion for connection with an exhaust tube.

SIDNEY JOHN CHERRY. LEO CARL WERNER. WILLIAM JOHN KNOCHEL. 

